The present invention relates to a flywheel and, more particularly, to a torsion damping assembly for damping vibrations in a torque transmitting arrangement between an engine and an input part of a transmission in a motor vehicle.
An assembly is known which is designed to damp vibrations in a torque transmitting arrangement between an engine and an input part of a change-speed transmission. Such as assembly is disclosed, for example, in U.S. Pat. No. 4,901,596 issued on Feb. 20, 1990 to Reik et al. This known assembly comprises a first flywheel connected to an engine, a second flywheel connected to an input part of a change-speed transmission, and a damper including energy absorbing spring means operative to yieldably oppose rotation of the flywheels relative to each other.
Japanese Utility Model Application Second Publication 2-6285 discloses a torsion damping assembly which comprises a first flywheel connected to an engine, a second flywheel connected to a friction clutch, and a damper including spring means operative to yieldably oppose rotation of the flywheels relative to each other. In order to suspend action of the damper once there occurs rotation of the flywheels relative to each other by a predetermined angle when engine speed drops below idle speed, a lock-up mechanism including a centrifugal force responsive lock component is received in a radial bore of a rim of the first flywheel. The rim surrounds a reduced diameter portion of the second flywheel which is formed with two angularly distant lock component receiving spaces. According to this known torsion damping assembly, the damper is kept in a stressed state when the lock component is received in one of the lock component receiving spaces. Besides: the lock component is not always engaged with one of the lock component receiving spaces when the engine is stationary.
An object of the present invention is to provide a torsion damping assembly wherein flywheels are allowed to rotate relative to each other due to the action of a damper at an engine speed above a predetermined engine speed, but the action of the damper is suspended to render the flywheel as a unit upon and after starting the engine until the engine speed reaches the predetermined engine speed.